Zone temperature control system



Jan. 6,- 1942'. w. L. M GRATH ZONE TEMPERATURE'CONTROL SYSTEM 4 Sheets-Sheet 1 muumm ms I.

Filed July 11, 1938 attorney Jan. 6, 1942.

W. I MOGRATH ZONE." TEMPERATURE CONTROL SYSTEM Filed July 11, 1938 4 Sheets-Sheet -2 Jan. 6,1942. w. McGRATH ZONE TEMPERATURE CONTROL SYSTEM Filed July 11 1958- 4 Sheets-Sheet s MA/M I attorney Jan. 6, 1942, w. L. MCLGRATH ZONE TEMPERATURE CONTROL SYSTEM Filed July 11, 1938 4 Sheets-Sheet 4 ill-T figp g5 2110mm mnunmmmawm (lttorne q Patented Jan. 6, 1942 UNITED STATES Mlnneapo Jioneywell Regulator Company,

Minneapolis, Minn, a corporation of Delaware g t 1': Claims. This invention relates to temperature control systems for buildings and particularly for buildings which are dividedup into zones for conditioning the same.

It has long been the practice to divide a building into zones, to provide each zone with a valve means or equivalent for controlling the delivery of temperature changing fluid to thatzone, and to provide each zone with a temperature controller for controlling the valve means of that zone to maintain desired temperature conditions in each zone oi the building. In such arrangements, the temperature changing fluid delivered to the various zonesds usually obtained from a common source, such as a boiler, district steam supply or the lilge. It is found that quite often more than one temperature controller will call for a temperature change at a time, and upon doing so the temperature controllers open their valve means at substantially the same time thereby increasing greatly the demand for tempera ture changing fluid. Likewise, more than one temperature controller may become satisfled at a time to close ofl their associated valve means to decrease greatly the demand ior temperature changing fluid. This simultaneous opening and closing of the valve means causes the demand for temperature changing fluid to fluctuate widely'. It a boiler is utilized as the source of temperature changing fluid, its efllciency of operation is greatly reduced by these wide fluctuations and ii the fluctuations in demand are extremely wide, alternate poppin of the boiler and extreme'low ressures are likely to occur. It a district steam supply is utilized as the source of temperature changing fluid, these wide fluctua tionsin demand would increase greatly the cost of operation inasmuch as the cost of district steam varies with fluctuations in demand.

Accordingly, it is an object of this invention to provide a timing arrangement. in combination with a zone temperature control system to prevent the above difficulty by staggering theopening and closing movements of the valve means of the various zones.

More specifically, it is an object of this invention to provide a zone control system wherein a temperature controller associated with each zone operates a valve means for controlling the supply of temperature changing fluid to its zone and wherein timing means are provided for staggering the opening and closing movements of the valve means to maintain desired temperatures within each zone while maintaining the demand 55 Application. July 11, 1938, Serial No. 218,518

for temperature changing fluid substantially constant. I

The particular methods in which this sequence of operation is carried out also form objects of this invention.

' For a more thorough understanding ofthis invention, reference is made tothe accompanying drawings, inwhich I I Figure 1 discloses one form of this invention;

' Figure 2 sets forth a modified form for accomplishing substantially the same results as are accomplished in Figure 1;

Figure 3 shows a modifled form for accomplishing a slightly diflerent sequence of operation;

Figure 4 shows a further modification for obtaining still another sequence of control, and

Figure 5' shows a modification which in effect combines the principles oi Figures 3 and 4 into so a composite control system.

The control systems set forth in this application may be applied to a building having a plurality .0: zones the temperatures of which are to be maintained at desired values. A common source or temperature changing fluid, such as a boiler, may be utilized for supplying temperature chang- I ing fluid to the various zones.

In Figure 1, a header leading from some source of temperature changing fluid, such as a,boiler; not shown, or a district steam supply, is designated at III. From this header I 0 extend risers I I, I2, and I3 leading to,three zones of the build- I ing. These risers supply temperature changing fluid, which may be in the form of steam at a as desired pressure, to heat exchangers located in the various zones. The flow of temperature changing fluid through the risers II, I2, and I3 is 'controlled' 'by motorized zone valves I4, I5,"

and I6, respectively. When electric energy is 40 supplied to these valves, they are opened to supply steam to their respective zones, and when the supply of electric energy is interrupted'these valves close to stop the supply of steam to their respective zones. I

Valves I4, I5, and I6 are controlled by relays Ii, I9, and 20, respectively, which in turn are controlled by zone temperature responsive controllers 2|, 22, and 23, respectively. A timer generally designated at 24 operates in conjunction with 50 the zone temperature responsive controllers for controlling the operation of the relays I5, I9, and 20 to stagger the opening movements and the closing movements of the zone valves I4, I5, and I5 PATENT OFFICE Theftimer 24- may comprise a-rotor 2s m-j iiuenced by a field winding 21 connected across line wires 28 and 29 leading from some source of power, not shown. Rotor 26 operates a shaft 3| through areduction gear train 36. The shaft 3| carries cams 32, 33, and 34, the high dwells of these cams being spaced equi-distant with respect to each other. The cams 32, 33, and 36 operate pivoted levers 35, 36, and 31 which in turn operate mercury switches 38, 39, and 40, respectively. The switches 38, 39, and 48 contain electrodes 62, 43, 44, and 45. With the switches in the positions shown in Figure 1, the electrodes 42 and 43 are bridged, and when the high dwells of the cams operate the switches to the position opposite to that shown in Figure 1 the electrodes 44 and 45 are bridged. For pur-' poses of illustration it is assumed that'the shaft 3| and hence the cams 32,33, and 34 are rotated once every nine minutes. Hence every switch is operated every nine minutes and the operation of the switches 36, 39, and 40 are spaced three minutes apart.

Relay i6 may include a step-down transformer 48 having a primary 48 connected across line wires 26 and 29 and a secondary 56. This transformer is utilized for supplying power to the control circuit. The relay I8 also includes an operating coil for operating switch arms 52, 53, and 54 with respect to contacts 55, 56,.

and 51. The arrangement is such that when the operating coil 5| is energized the switch arms are moved into engagement with their respective contacts, and'when the operating coil is deenergized the switch arms are moved out of engagement withv their respective contacts by means of springs, gravity, or other -means, not shown. Relays E9 and 26 have exactly the same construction as the relay l8 and therefore a further de-' scription of these relays is not necessary.

For purposes of illustration, the temperature responsive controllers 2|, 22, and 23 are shown to be of the outdoor temperature typ disclosed in Patent 2,065,835 granted to D. G..Taylor on December 29, 1936. These controllers are located outside of the building adjacent to the zones which they are to controlso that they will be affected by the same atmospheric conditions as afiect their respectiv zones.

The outdoor controller 2| may comprise a metallic block 66 which is suitably hollowed out to receive a bimetallic element 6| and a spring arm 62 carried by a post 63. The spring arm 62 normally engages the bimetallic element 6| as shown in Figure '1. The spring arm 62 carries a contact 64 which is adapted to engage an adjustable stationary contact 65 and the thermostatic element 6| carries a contact 66 adapted to engage an adjustable stationary contact 61. An electric heater 68 heats the metallic block 68 for maintaining the block at desired tem-' peratures. The structure of the temperature controller thus far described is housed in a suitable enclosure 69 to protect the same from the elements. sumed that the stationary contacts 65 and 61 are so adjusted that upon a decrease in temperature of the block 66 the contact 64 first engages the above referred to Taylor patent, the rheostat 10 is adjusted so that the supply of heat to the out- .door controller and the supply of heat to the zone of the building controlled thereby is proportional to the heat loss from the temperature responsive controller and the heat loss from that zone of the building.

Assume now that the temperature of the outdoor controller decreases to 66 whereupon contacts 64 and 65 and contacts 66 and 61 are in engagement. When the cam 32 rotates to a position to operate the switch 38 to bridge the electrodes 44 and 45, a starting circuit for the operating coil 5| of the relay is completed. This starting circuit may be traced from the secondary 56 of the transformer 48 through wires 1| and 12,- contacts 65, 64, 66, and 61, wire 13, electrodes and 44 of the switch 38, wires 14 and 15, operating coil 5|, and wire .16 back to the transformer 56. Completion of this circuit energizes the operating coil 5| to move the switch arms 52, 53, and 54 into engagement with their respective contacts 55, 56, and 51.

Movement of the switch arm 53 into engagement with the contact 56 completes a circuit from the line wire 28 through wire 18, contact 56, switch arm 53, wire 19, motorized valve I4, and wire 80 back to the other line wire 29. Hence when the relay "3 is pulled in, the motorizedvalve I4 is opened to supply steam to its associated zone.

Movement of the switch arm 54 into engagement with thecontact 51 completes a circuit from the line wire 28 through wire 82, contact 51, switch arm 54, wire 83, adjustable rheostat 18,

wire 84, heater element 68, and wire 85 back to the,

other line wire 29. Accordingly, whenthe relay I8 controller is energized to supply heat to the same.

Movement of the switch arm 52 into engagement with the contact 53 completes a maintaining circuit for the operating coil 5| which is independent of the contacts 66 and 61. This maintaining circuit may be traced from the secondary through wires H and 12, contacts 65 and. 64, spring arm 62, and bimetallic element For purposes of illustration,- it is asheating 'efiect thereof. As is set forth in the 75 6|, wires 81. and 88, contact 55, switch arm 52, wires 89 and 15, operating coil 5|, and wire 16 back to the secondary 50. Completion of this maintaining circuit maintains the relay l8 energized until such time as th temperature of the outdoor controller 2| rises to to separate the contacts 64 and 65.

It is here noted'that the electrodes 44 and 45 are included in the starting circuit of the relay I8 so thatit is possible to pull in the relay l8 only at predetermined time intervals. After the relay has once been pulled in in the manner outlined above, it remains in at least until the temperature. responsive controller 2| is satisfied. Since the cams 32, 33, and 34 are spaced apart in operation, it is therefore possible to open the various zone valves |4, |5, and I 6 only at predetermined intervals. Accordingly, large fluctuations in demand for steam caused by simultaneous opening of a plurality of valves is entirely eliminated while substantially constant temperatures are maintained in each zone.

When the switch 38 is inv the position shown, in Figure 1, the electrodes 42 and 43 are bridged to complete a second maintaining circuit for the operating coil 5|, this second maintaining circuit being traced from the secondary 50 through wire 1|, electrodes 42 and 43, wire 86, contact 55, switch arm 52, wires 86 and 15, operating coil 5|,

' the shaft Summarizing briefly the operation of Figure 1,

it is seen that the zone valves can only be opened at predetermined time intervals providing their temperature responsive controllers are calling for a temperature change, and that the zone valves can be closed only at predetermined time intervals providing their respective temperature responsive controllers are "satisfied. Accordingly, large fluctuations in the demand for temperature changing fluid caused by simultaneous open- .ing or closing of zone valves is eliminated and defired temperature conditions are at all times maintained in each zone. Referringnow to Figure 2, a different control arrangementis utilized for obtaining substantially the same sequence of operation as is obtained in Figure 1. ure 2 is shown to be applied to a building having four zones. Motorized zonevalves I00, IOI, I02, and I03 are utilized for controlling the supply of temperature changing fluid, such as steam, to their associated zones. valves may be of thetwo position type having .a maintaining switch for moving the-valves to 3 their extreme positions and for maintaining the valves in the extreme positions until they are started to the other extreme p sitions. These valves may take the ,form shown' and described in application Serial No. 15,965 filed by Carl G. Kronmiller on April 12, 1935.

The zone valves I00, IOI, I02, and I03 are controlled by zone temperature responsive controllers in the form of zone thermostats I04, I05, I06, and 101, respectively. The zone valves are also controlled by a timer generally designated at I00 which may comprise a rotor'I00 influenced by a field winding IIO connected across line wires III and H2. The rotor I09 operates a shaft II4 through a reduction gear train H3, carrying cams H5, H6, H1, and H6. The cams H5, H6, H1, and H8 operate pivoted levers II9, I20, I2I, and I22, respectivel which in turn operate mercury switches I23, I24, I25, and I26. When the high dwells of the cams operate' the levers, the switches are tilted to a position to cause bridging of the electrodes there- I in. For-purposes of illustration, it. is assumed that the shaft-I I4 and hence the cams are rotated once every eight minutes and that the 'cams .II5, H6, H1, and H8 are spaced equi-distant. .Hence each switch is --moved to a closed position every eight minutes and the closing movements of. the switches are staggered at two minute intervals.

Each of the zone thermostats may comprise a thermostatic element I30 for operating a switch arm I3I with respect to stationary contacts I32 These motorized heat by the zone thermostat the temperature .of the zone valve I00 decreases to 70 whereupon the switch arm -I3I of the zone thermostat I 04 engages the contact I32.. When the switch I23 is operated by the cam II5 to bridge the electrodes therein,:a circui is completed from the'motor I00 through wire I35, electrodes of the switch I23, wire I36, thermostatic element I30, switch arm I3I, contact I32, and wire I31 back to the motorized valve I00. Completion of this circuit starts the motorized valve I00 towardsan open position and the opening movement of the motorized valve is continued to the open position by means of a maintaining switch contained therein; Accordingly, upon a call for I04, the zone valve I00. is opened when the switch I23 is moved to a closed position. Since it is only possible to open the zone valve when the switch I23 is closed, the zone valve I00 may be opened only at predetermined intervals. The same is true for the other zone valves IOI, I02, and I03, and since the operations of the switches I23, I24, I25, and I26 are staggered as set forth above, the opening move- The control system of Figments of the various zone valves must necessarily be staggered. This effectively prevents the simultaneousopening of the various zone valves and therefore prevents wide fluctuations in the demand for steam caused by simultaneous opening of the zone valves.

When the temperature of the zone controlled by zone valve I00 increases to 72, the switch arm I3I of .the zone thermostat I 04 moves into engagement with the contact I33. When the mercury switch I23 is tilted by the cam II5 to bridge the electrodes therein,'a circuit is completed from the motorized valve I00, through wire I35, electrodes of the mercury switch I23, wire I36, ther mostatic element I30, switch arm I3I, contact I33, and wire I38 back to the motorized valve I00. Completion of this circuit starts the zone valve towards a closed position and the closing-movement is continuedto theclo'sed position by the maintaining switch contained in the zone' valve. Hence when the zone temperature is satisfied, the zone valve is moved to a closed position when the mercury switch-I23 is closed. Such is the case for the other zone valves and since the oper-,-

' temperature responsive controllers are calling for a temperature change and that the zone valves can be closed only at predetermined time intervals providing their respective temperature responsive controllers are satisfied. Accordingly,

and I33. When the space temperature decreases,

say to 70,

or closing of the zone large fluctuations in the demand for temperature changing fluid caused by simultaneous opening valves is eliminated and desired temperature conditions are at all times maintained in each zone. It is also seen that the modification shown by Figure 2 provides for substantially the same sequence of operation as is obtained by that of Figure 1.

Figure 3 as far as structure is concerned is substantially the same as Figure 1, and therefore like reference characters for like parts have been utilized. Figure 3, however, differs from Figure 1 in the construction of the switches 36, 39, and 40 and the electrical connections between the relays the outdoor controllers 2|, 22, and 23. These difierences in connections give a slightly difierent sequence of operation.

Switches 38, 39, and 48 are provided with tw electrodes MI and I42 which are bridged momentarily at predetermined time intervals. If,

revolution every nine minutes, the switches 38, 39, and 4|! are momentarily closed every nine minutes and the closing movements of these switches are staggered by three minutes.

Assumenow that the temperature of the outdoor controller 2| of Figure 3 decreases to 66, whereupon contact 64 engages contact 65 and contact 66 engages contact 6]. A starting circuit ior. the operating coil of the relay I8 is completed. This starting circuit may be traced from the secondary 58, through wire I43, contacts 65, 64, 66, and 61, wires I44, I45, and I46, operating coil 5|, and wire I4I back to the secondary 56.

as in Figure 1, the cams 32, 33, and 34 make one Completion of this circuit energizes the-operat- I ing coil 51 to move the switch arms 52, 53, and 54 into engagement with their respective contacts 55, 56, and 51. Movement of the switch arm 53 into engagement with the contact 56 opens the zone valve I4 and movement of the switch arm 54 into engagement with the contact 51 energizes the heater element'fifi. Since this starting circuit for the operating coil 5| is independent oi the switch 38, the outdoor controller 2| may at any time open its associated zone valve and energize its heater element 68 when the temperature thereof decreases to 66.

Movement of the switch arm 52 into engage- .ment with its contact 55 completes a maintaining the outdoor controller is satisfied.

The switch 38 provides a timed auxiliary starting circuit for therelay to pull in the relay I8 whenever the contacts 64 and 65 of the outdoor controller are in engagement. Assume now that the temperature of the outdoor controller 2| is below 70 so that the contacts 64 and 65 are in engagement and that the switch 38 is moved to a position wherein the electrodes HI and I42 are bridged. The timed auxiliary starting circuit I v completed thereby may be traced from the sec- I ondary 55, through wire I43, contacts 65 and 64, 'spring member 62, thermostatic element 6|, wires I48 and I5I, electrodes IM and I42, wires I52,

,|45,'and I46, operating coil 5|, and wire I41 back to the secondary 56. Accordingly, if the outdoor controller 2| is not satisfied which causes the contacts 64 and 65 to be engaged, the time ope ated switch 38 may pull in therelay I8 to supply heat to the zone and to the outdoor controller and this supply of heat will be continued until such time as the outdoor controller becomes satisfied whereupon the contacts 64 and 65 disengage. The tendency of this system is therefore to pull in the relay I6 and supply heat to the building and to the outdoor controller at predetermined time intervals. andto maintain the supply of heat to the zone and to the outdoor 2,268,761 I8, I9, and '20, the switches 38, 39, and 40 and controller until the outdoor controller becomes satisfied. Since the operationsoi the switches 38, 39, and 48 are staggered, the timed opening of the zone valves I4, I5, and I6 are staggered to prevent fluctuations in the demand for steam caused by the simultaneous opening of th zone valves. The outdoor controllers 2|, 22, and 23 can open their respective zone valves it the temperature therein should decrease to 66 regardless of the position of the timer 24 to take care of sudden changes in heating load.

Summarizing brieflythe operation of Figure 3, it is seen that normally the zone valves are opened at predetermined time intervals by the timer and remain open until their associated temperature responsive controllers are satisfied. Since the opening movements of the zone valves are staggered, large fluctuations in demand for temperature changing: fluid caused by simultaneous opening ofthe zone valves is eliminated and desired temperature conditions are at all times maintained in each zone. The staggered opening of the zone valves also tends to make the closing movements thereof staggered. Further, it is seen that the various temperature responsive controllers may open their associated zone valves independently of the timer if an abnormal load condition 8110111.; occur which may be caused by a morning pick-up period or a sudden change in heating load.

The construction shown in Figure 4 is sub-- stantially the same as that shown in Figures '1 and 3 and like references for like parts have been utilized in these three figures. Figure 4 differs from Figures 1 and 3 in the construction of the switches 38, 39, and 46 and in the wiring connections between the relays I8, I9, and 20, the switches 38, 39, and 40 and the outdoor controllers 2|,22, and 23. The switches 38, 39, and 40 are shown to include two electrodes I 53 and I54 which are normally bridged and which are normally unbridged at predetermined time intervals. The time sequence of the timer 24 of Figure 4 may be the same as that of Figures land 3.

ating coil 5|'of the relay I8 is thereupon com pleted and may be traced from the secondary 50 through wire I55, contacts 65, 64, 66, and 61, wires I56 and I5'I, operating coil 5|, and wire I58 back to the secondary 50. Completion of this circuit energizes the operating coil 5| to move the switch arms 52, 53, and 54 into engagement with their respective contacts 55, 56, and 51. Movement of the switch arms 53 and 54 into engagement'with the contacts 56 and 51 opens the zone valve I4 and energizes the heater element 68 to supply heat to the zone'and to the outdoor controller 2 I.

Movement of the switch arm 52 into engagement with the contact 55 completes a maintaining circuit for the operating coil 5| which may be traced from the secondary 50 through wire I55, contacts 65 and 64, spring member 62, thermostatic element 6|, wire I59, electrodes 53 and I54 of the mercury switch 38, wire I60, contact 55, switch arm 52, wires I6I and I53, operating coil 5|, and wire I58 back to the secondary 50. The completion of this circuit maintains the relay 5| energized until such time as the outdoor controller 2| rises in temperature to 70to separate the contacts 64 and 65 or until the mercury switch 38 is tilted to unbridgethe electrodes its and :54. Switch as normally interrupts the maintaining circuit to shutdown the zone valve I4 and to interruptthe supply of heat to the outdoor controller 2f"'at predetermined time intervals and since the switches 38, 39, and 48 are staggered in operation valves I4, I5, and I8 are staggered to prevent large fluctuations in the demand for steam caused by simultaneous closing of the zone valves. The zone valves I4, I5, and I8 may be closed by their associated outdoor controllers 2|, 22, and 23 when the temperature thereof rises to 70 regardless ofv the position of the timer 24.

Summarizing briefly the operation of Figure 4, it is seen that the zone valves are opened upon a call for temperature change by their respective temperature responsive controllers and that the zone valves are normally closed in sequence by the timer. Accordingly, large fluctuations in the demand for temperature changing fluid caused by simultaneous closing of the zone valves is .eliminated and desired temperature conditions are at all times maintained in eachzone. Since the closing movements of the zone valves are staggered, the-opening movements thereof also tend to be staggered so that fluctuations in the demand for temperature changing fluid caused by simultaneous opening of the zone valves is substantially eliminated also.

It is found that .the control system set forth in Figure 3 works exceptionally well during mild weather and that the control system of Figure 4 works exceptionally well during severe weather. The control system of Figure 5 combines the systems of Figures 3 and 4 into a composite structure to provide an improved'sequence of operationregardless of whether the weather be mild or severe. In Figure 5; during mild weather the system thereof operates substantially the same as that of Figure 3 and it operates substantially the same as that of Figure 4 in severe weather.

Referring now to Figure 5, the-structure disclosed therein is substantially the same, as that of Figures 1, 3, and 4 and therefore like reference characters have been-utilized for like'parts. The outdoor controllers M, 22, and 23 of Figure 5 differ somewhat from those of Figures 1, 3, and 4. In Figure 5, the outdoor controller 2| is shown to comprise ametallic block I18 hollowed out to receive a thermostatic element "I mounted on a post I12. Secured to the bimetallic element I1I is a substantially U shapedsprlng member I13. The spring member I13 carries a contact I14 adapted to engage an adjustable stationary contact I15 and the bimetallic element 11! carries a contact I18 adapted to engage an the closing of the zone by the timer 24 include electrodes I83, I84, I85, and I88. When the switches are in the positions shown in Figure '5, electrodes I85 and I88 are bridged, and when the switches are tilted to the opposite position electrodes I83 and I84 are momentarily bridged. The timing sequence of the switches 38, 33, and 48 may be the same as that of Figures 1, 3, and 4, so that the desired staggered operation may be obtained. When .the outdoor temperature is temperature of the outdoor controller will tend to be higher than when the outdoor temperature is severe. Accordingly, during mild weather the contacts I14 and I15 of the outdoor controller 2| provide the primary control, while during severe weather the contacts I18 and I11 provide the primary control.

Assume now that the outdoor temperatureis relatively mild and that the temperature of the outdoor controller assumes a value between 68 and 70, whereupon the contacts I14 and I15 and the contacts I18 and I19 are in engagement. When themercury switch 38 is. tilted to a position to bridge the electrodes I83 and I84, a starting circuit for the operating coil 5| is completed and may be traced from the secondary 58 through wire I98, contacts I15. and I14, spring member I13, contacts I18 and I19, wires HI and I92,

electrodes'l84 -and I83, wires I93, I94,and I95, operating coil 5|, and wire I98 back to the secondary 58. Completion of this starting circuit energizes the operating coil 5! to move the switch arms 52', 53, and 54 into engagement with contacts 55, 58, and 51. Movement of the switch arms 53 and 54 into engagement with contacts 58 and 51 opens the zone valve I4 to supply heat to the zone and energizes the heater element I88 to supply heat to the outdoor controller 2|.

Movement of the switch arm 52 into engagement with contact 55 completes a maintaining circuit for the operating coil-5i which is independent of the electrodes I83 and I84 of the switch 38, which circuit may be traced from the secondary 58 through wire I98, contacts I15 and I14, spring member I13, contacts I18 and I19, wires 'I9I and I91, contact 55, switch arm 52, wires I98 and I95, operating coil 5|, and wire I98 back to the secondary 58. Completion of this circuit maintains the operating coil 5i energized her I13 also carries a contact I18 adapted to engage an adjustable stationary contact I19. Upon until such time as the temperature of the outdoor controller 2| rises above to separate contacts I14 and I15.

Accordingly, during, mild weather, the relay I8 is pulled in to supply heat to the zone and to the outdoor controllerat predetermined time intervals providing the outdoor controller is not satisfled and is maintained in until the outdoor"controller 2| becomes satisfied. *Since the switches 38, 39, and 48 are sequentially operated, the openings of the zone valves during mild weather are staggered to eliminate large fluctuations in dea decrease in temperature, the contact I14 first engages the contact I15 at 70, the contact I18 then disengages the contact I19 at 68, and the contact I18 then engages the contact I11 at 66. Upon an increase in temperature in the outdoor controller 2|, contacts I18 and I11 sepairate at 66", contacts I18 and I19 engage at 68, and contacts I14 and I15 disengage at 70. A heater element I88 supplies heat to the outdoor controller 2| and located in series with the heater element I88 is an adjustable rheostat 18 for admand for temperature changing fluid caused by simultaneous opening of the zone valves. Since the opening movements of the zone 'valves are thus staggered, the closing movements of the same will also tend to be staggered whereby fluctuations in the demand for temperature changing fluid caused by simultaneous closing of the valves is substantially eliminated.

Assume now that the weather conditions are I severe, whereupon the outdoor temperature conjusting the amount of heat given off by the heater element I88. A suitable casing I8I protects the outdoor controller from the elements. The mercury switches 38, 39, and 48 operated troller will assume lower temperature values.

When the temperature of the "outdoor controller 2I decreases to 66, the contacts I14 and I15 and the'contacts I18 and I11 are engaged to complete mild, the

a starting circuit for the. operating coil I which may be traced from the secondary 58 through wire I90, contacts II5, I'll, I18, and III,wires 288, I94, and I95, operating coil 5I,and wire I96 back to the secondary 50. Completion of this circuit energizes the operating coil ii to move the switch arms 52, 53, and 54 into engagement with the contacts 55, 55, and 51. Movement of the switch arms 58 and 54 into engagement with the contacts 55 and 51 opens the zone valve I4 to supply heat to the zone and energizes the heater element I88 to supply heat to the outdoor controller 2 I.

Movement of the switch arm 52 into engagement with the contact 55 completes a maintaining circuit for the operating coil 5I which may be traced from the secondary 50 through wire I98, contacts "5 and I'll, spring member I18, bimetallic element III, wire 202, electrodes,

I85 and I86, it being understood that the contacts Ill and H5 are normally engaged during severe weather.

Since the switches 88, 39, and 40 are sequentially operated, the opening movements of the zone valves II, I5, and I6 are staggered during severe weather to prevent large fluctuations in ing movements of the zone valves to eliminate large fluctuations in the demand for temperature changing fluid caused by simultaneous opening or closing of a plurality of zone valves. In several of the modifications of this invention, out--. door controllers have been described for controlling the temperature in the various zones but it is within the contemplation of this invention to substitute zone thermostats therefor as was done 'the demand for temperature changing fluid caused by simultaneous closing of the zone valves.

Since the closing movements of the zone valves are staggered during severe weather, the opening movements thereof will also tend to be staggered, whereupon fluctuations in the demand for temperature changing fluid caused by simultaneous opening of the zone valves is substantially eliminated. The outdoor controller may close of! the zone valves when the temperature thereof increased to to separate the contacts I" and I15.

The operation of Figure 5 may be summarized briefly as follows: in mild weather the zone valves are opened at'predetermined time intervals providing their temperature responsive controllers are not satisfied and remain open until their associated temperature responsive controllers are satisfied. The sequential opening of the.

zone valves during mild weather also tends to cause sequential closing thereof, and accordingly large fluctuations in the demand for temperature changing fluidcaused by simultaneous open- \ing or closing of the zone valves is eliminated. In severe weather, the temperature responsive controllers open their associated zone valves upon a call for temperature change and the zone valves are closed at predetermined time intervals which also tend to open the zone valves at predetermined timeintervals. Accordingly, during severe weather large fluctuations in the demind for temperature changing fluid caused'by simultaneous opening or closing of the zone valves is eliminated. In both instances, desired temperatures are maintained in each zone at all times.

in Figure 2. Also, this invention is applicable to cooling systems as well as heating systems and the control of a cooling system by the control systems defined herein is also within the contemplation of this invention. The control systems .of this invention may also be utilized for purposes other than controlling temperature conditions ln zones of a building and such uses are alsowithin the contemplation of this inven tion.

Although for-purposes of illustration, several forms of this invention have been disclosed, other forms thereof may become apparent to those'skilled in the art upon references tothis disclosure and therefore this invention is to be limited only by the scope of the appended claims and prior art.

I claim as my invention:

1. In a control system for a temperature changing systemconditioning a plurality of zones and having a source of temperature changing fluid and means for supplying temperature changing fluid to thevarious zones, the combination of, valve means for each zone for controlling thesupply of temperature changing fluid to its associated zone, electrical means-for opening and closing the valve means including an operating coil and a maintaining switch which is closed when the valve means is opened, thermostatic means for each zone and including a pair of switches sequentially closed upon a temperature change in one direction, electrical connections for each zone between the second to close switch and the operating coil for open ng the valve means of that zone and electrical connections for each zone between the flrst to close switch, the maintaining switch and the operating coil to maintain the valve means of that zone open until theflrst to close switch opens, normally open time operated switching means asso-- the opening of the valve means of the various zones are staggered and desired temperatures is maintained in each zone.

From the above it is seen that this invention contemplates a temperature control system-for a building'having a plurality of zones wherein the zone valves are controlled by temperature .responsive controllers to maintain desired tem- 2. In a control system fora temperature changing system conditioning a plurality of zones and having a source of temperature changing fluid and means for supplying temperature changing fluid to the various zones, the combination of, valve means for each zone for controlin coil and a maintaining switch which is closedwhen the valve means is opened, thermostatic means for each zone and including a pair of switches sequentially closed upon a temperature change in one direction, electrical connections for each zone between the secondto close-switch peraturesineach'zone'and wherein timing means and the operating coil for opening the valve are provided for staggering the'opening and closmeans of that zone and electrical connections for switch and the operating coil to maintain the valve means open until the normally closed time operated switching means opens, whereby the c os of the valvemeans ofthe various zones is staggered and desired temperatures are main-' tained in each zone. a l

3. In a control system fora temperature chang-j ing system conditioning a plurality of zones and having a source of temperature changing fluid *fiui'd to the various zones,

and means for supplying temperature changing fluid to the various zones, the combination of, valve means for each zone for controlling the supply of temperature changing fluid to its associated zone, electrical means for opening and closing the valvemeans including an operating coil and a maintaining switch which is closed when the valve means is opened, thermostatic means for each zone and including a pair of switches sequentially closed upon a temperature change in one direction, electrical connections for each zone between the second to close. switch and the operating coil for opening the valve means of that zone and electrical connections for each zone benections for each zone between the first to close switch, the normally open time operated switch and the operating coil for opening the valve means at predetermined" time intervals when the first to close switch is closed, whereby the opening of the valve means is staggered and desired temperatures re maintained in each zone.

5. In a con rol system for a temperature changing system conditioning a plurality of zones and j liaving a. source of temperature changing .fiuid \a nd means for supplying temperature changing the combination of, valve-means for each zone for controlling the supply of temperature changing fluid to its associated zone, electrical means for opening and closing the valve means including an operating coil and a maintaining switch which. is closed whenthe valve means is opened, thermostatic means for each zone and including a 'pair of switches sequentially closed upon a temperature.

change in one direction, electrical connections for each zone between the second to close switch tween the first to close switch, the maintaining switch and the operating coil to maintain the valve means of that zoneopen until the first to close switch opens, normally open time operated switching means associated'with each zone and sequentially closed with respect to the various zones, means for including the normally open time operated switching means in the first mentioned electrical connections to allow opening of the valve means only. at predetermined time intervals, whereby the opening of the valve means of the various zones is staggered and desired temperatures are maintained in each zone, normally closed time operated switching means associated with each zone and sequentially opened with respect to the various zones, and electrical connections for each zone between the normally closed time operated switching means, the maintaining switch and the operating coil to main tain the valve means open until the normally closed time operated switching means opens, whereby the closing of the valve means of the various zones is staggered and desired temperatures are maintained in each zone.

4. In a control system for a temperature changforeach zone between the second to close switch ing system conditioning a plurality of zones and having a source of temperature changing fluid and means for supplying temperature changing fluid to the various zones, the combination of, valve means for each zone for controllingthe supply of temperature changing fluid to its associated zone, electrical means for opening and closing, the valve means including an operating coil and a maintaining switch which is closed when the valve means is opened, thermostatic means for each zone and including a pair of switches sequentially closed upon a temperature change in one direction; electrical connections for each zone between the second to close switch and the operating coil for opening the valve means of that zone and electrical connections.

the maintaining switch andjthe operating coil 75 closed time operated switching means associated and the operating coil for opening the valve means of that zone andelectrical connections foreach zone between the first to close switch. the maintaining switch and the operating coil to maintain the'valve means of that zone open until the first to close switch opens, normally closed time operated switching means associated with each zone and'sequentially operated with respect to the various zones, and means for including the normally closed time operated switching means in the last mentioned electrical coinnections for closing the valve means at predetermined intervals if the second to close switch is not closed, whereby the closing of the valve means is staggered and desired temperatures are maintained in'each zone.

6. vIn a control system for a temperature changing system conditioning a plurality of zones and having a source of temperature changing fluid and means for supplying temperature changing fluid to the various zonesQthe combination of, valve means ior each zone for controlling the supply of temperature changing fluid to its associated zone, electrical means for opening and closing the valve means including an operating coil and a maintaining switch which is closed when the valve means is opened, thermostatic means for each zone and including a .pair of switches sequentially closed upon a temperature change in one direction, electrical connections and the operating coil for opening the valve means of that zone and electrical connections for each zone between the first to close switch,

the maintaining switch and the operating coil. to maintainthe valve means of that zone open for-each zone between the first to close switch,-

the normally open time operated switch and the operating coil for opening the valve means at predetermined time intervals when the first to.

close switch is closed, wherebythe opening of the valve means-is staggeredv and, desired temperatures are maintained in each zone, normally,

with each zone and sequentially operated with respect to the various zones, and means for including the normally closed time operated switching means in the-last mentioned electrical connections for opening the valve means at predetermined intervals if the second to close switch is not closed, whereby the opening of the valve means is staggered and desired temperatures are maintained in each zone.

7. In a control system for a temperature changing system conditioning a plurality of zones and having a source of temperature changing fluid and means for supplying temperature changing fluid to the various zones, the combination of, valve means for each zone for controlling the supply of temperature changing fluid to its associated zone, electrical means for opening and closing the valve means including an operating coil and a maintaining switch which is closed when the valve means is opened, thermostatic means for each zone and including a pair of switches sequentially closed upon a temperature change in one direction, electrical connections for each zone between the second to close switch and the operating coil for opening the valve means of that zone and electrical connections for each zone between the first to close switch, the maintaining switch and the operating coil to maintain the valve means of that zone open until the first to close switch opens, and

timecolitrolled means associated with said electrical connections in a manner to control only the time in which movements of the various valve means take place under the controlof their corresponding thermostatic means, said time controlled means serving to stagger, movements ir the same direction of said valvegmeans.

8. In a control system for "a temperature changing system congtioning a plurality of zones and having a source of temperature changing fluid and means for supplying temperature changing fluid to the various zones,.the combination of, valve means for, each zone for controlling the supply of temperature changing fluid to its associated zone, two stage thermostatic means 1 for each zone, each thermostatic means controlin one direction to the second stage settingtherew of and to close said valve means when the associated with each valve means and capable of closing it before the corresponding thermostatic means is completely satisfied, each first control means being incapable of preventing opening of its valve means by the corresponding thermostatic means, second control means associated with each valve means and capable of causing opening thereof even when the corresponding thermostatic means is not demanding such opening movement provided that the corresponding ther-' mostatic means is not completely satisfied, and time controlled means for operating said first and second control means in a manner to stagger opening and closing movements of said valve means.-

10. In a control system for a temperature changing system conditioning a plurality of zones, a source of heating fluid and means for supplying heating fluid to the various zones, the combination .of, electrically operated valve means for each zone for controlling the supply of heating fluid to its associated zones, an outdoor controller tor eachrzone having electrical heating means and thermostatically operated switching means, means including electrical connections between the thermostatically operated switching means, the electrical heating means and the electrically operated valve means for each zone foropening and closing the electrically operated valve means andfor simultaneously energizing and deenergizing the electrical heating means to maintain desired temperatures in each) zone, and time controlled switching means associated with the electrical connections of each zoneior controlling movements of the zone valve means and also controlling the electrical heating means for said outdoor controllers, said time "controlled switching means being connected into the'corresponding thermostatic switching means and serving to stagger opening and closing movements of the various valve means.

11. In a control system Ior't'emperature changing system conditioning a plurality of zones having a source or temperature-changing fluid and perature varies in the opposite from: w the first stage setting of the thermostaticimeans,

control means associated with eachtlierniostaticf means for closing the corresponding valvegmeims independently of the first stage or thethermo-f static means but dependently of the second stage of the thermostatic means, and time controlled means for sequentially actuating control means for thereby closing at spaced intervals only the valve means controlled by the static means which' are on their first stagelfgg 9. In a control system for a. temperature changing system conditioning a plurality. of zones and having a source of temperature changing fluid and means for supplying temperatiii'c changing fluid to the various zones, the combination of, valve means for each zone for controlling each thermostatic means being constructed and arranged to openits corresponding valve means. at any time upon' demand for temperature changing medium and to close it when the thenmeans for supplying said fluid to the various zones-the combination of, a plurality of two position valve means, one for each zone for controlling the supply ottemperature changing fluid to its associated zone. a zone thermostatic means for each valve means, a secondary control means for each zone, means for operating said secondcontrol means in sequence. and connections .tor each zone interconnecting the-valve means,

thermostatic means and secondary control means in such manner that both the thermostatic means and the secondary control means must be demanding movement or the valve means to a spective oi the action of said secondary control means and until such time as the thermostatic means demands movement of the valve means to its second position.

12. In a control system for a temperature changing system conditioning a pluralityo! zones having a source of temperature changing fluid and means for said fluid to the va.ri-

ous zones, the combination or, a plurality oi. two position valve. means,i"on 'e for each zone for con- .mostatic means is satisfied. first control means 7 5 trolling the supplyflo'iitemperature changing fluid zones, the combination of, a

' of said secondary control its associated zone, a

flandrmeans for supplying i tion valvemeans. one

to its associated zone, a zone thermostatic means for each valve means, a secondary control means for each zone, means for operating said secondary control means. in sequence, and connections for each zone interconnecting the valve means, thermostatic means and secondary control means in such manner that both the thermostatic means and the secondary control means must be demanding movement of the valve means to open position to bring about the valve means,

action of said secondary control means and until such time as the thermostatic means demands movement of the valve means to its closed position.

opening movement of. the valve means thereafter remaining in its open position irrespective of the l3. In a /control system for a temperature andthe secondary control means must be de-- manding movement of the valve means to closed position to bring about closing movement of the valve means, the valve means thereaiterremaining in its closed position irrespective oi the action time as the thermostatic. ment or the valve means 14. In a control system for a temperature changing system conditioning a plurality of zones having a source of temperature changing fluid and means for supplying said fluid to the various to its'open position.

zones, the combination-of/a plurality of two posltion valve means, one for each zone for controlling the supply of temperature changi g fluid to means and until such means demands .move-' thermostatic means for.

each zone, each thermostatic means; having at least three operating v means opening position,'a valve means closing position, and an' intermediate positi connections between each thermostatic means'by means opens and closes thermostatic means valve opening and .valve closing positions, a secondary control means for each zone. means to operate which the thermostatic means. thermostatic means and secondary control means by which the secondary control means is enabled to move d valve means to one of its positions only when the thermostatic'means is in its intermediate'pcsition.

15. In a control system for; a temperature changing system conditioning'a plurality of zones having a source oi temper ature changing saidfluid to the various zones-the combination of, a plurality of two posiling the supply oi temperamre positions including a valve valve means and its associated for each aoneior contpol- WW- w its'.valve means when the respectively moves to i s all-oi said secondary" control means sequence and connectionabetween' each valve having a source or control means for each 7 zones. the combination .tion valve means, onei'or each ling the supply of temperature connections between each .val

. static mean'aia its associated zone, a thermostatic means for each zone, each thermostatic-means having at least three operating positions including a valve means opening position, a valve means closing position, and an intermediate position, connections between each valve means and its associated thermostatic means by which the thermostatic means opens and closes its valve means when the thermostatic means respectively moves to its valve opening and valve closing positions, a secondary control means for each zone," means to operate all of said secondary control means in sequence and connections between each valve means, thermostatic means and secondary control means by which the secondary control move said valve means to its open position only when the. thermostatic means is in its intermediate position.

16. In a control system for a temperature system conditioning a plurality of zones temperature changing iiuigi and means for supplying said fluid to the various zones, the combination of, a plurality of two position valve means, one for each zone for controlling the supply or its associated zone, a thermos zone, each thermostatic m as having at'least three operating positions including a valve means opening position, a valve means closing position, and an intermediate position, connections between each valve means and its associated therm'ost'atic means by which the thermostatic means opens and closes mostatic m tively moves to its valve opening and valve closing zone, means to operate all of said secondarycontrol means in sequence. and connections between each valve means, thermostatic means andsecondary control means by which the secondary control' means is enabled to move said valve means to its closed position only .when the thermostatic means is in its intermediate position.

g said fluid to the various oi, a plurality of two posizone for controland means for sup its associated zone, a thermostatic means for each zone, each thermostatic means having at least three operating positions including a'valve means openinfi-position, a valve means closing pomtion, and an intermediate connections be tween each valve means and its associated thermostatic means by which the thermostatic means opens and closes its valve opening and valve c positions, a secondary control means 101" each none.v means to operate all or said secondary control means in sequence, and

static "means and which move aaid-vaivemeans closed andviceverse when thethermoin its intermediate wnmm 1. uecaarn.

means is enabled to temperature changing fluid to he means for eachits valve means when the therposition, a secondary v I ;means when the thermostatic means respectively moves to its valvemeans, thermo- 

